Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of USANA Health Sciences (USNA 0.13%) gained as much as 19% after the company delivered an impressive fourth quarter earnings report.

So what: The multilevel marketer of health supplements said quarterly earnings per share improved to $1.41, better than estimates of $1.37, while sales moved up 10.5% to $186.3 million, also beating the experts' mark. CEO Dave Wentz credited the successful execution of recent company initiatives for the standout quarter. USANA's outlook for 2014 was also promising: the company sees revenue of $790 to $810 million and EPS of $5.80 to $5.95. Analysts had expected sales of just $750.5 million and a per-share profit of $5.63.

Now what: Beating estimates is always a strong sign for a company, but USANA's report comes at a particularly crucial time, just weeks after China accused rival Nu Skin Enterprises of operating as a pyramid scheme. That sent shares of Nu Skin and other industry stocks plummeting as they tend to trade in tandem and are often subject to similar accusations. However, USANA's report today makes it clear that the stock's prospects are solid and growing. As CFO Paul Jones said in a press release, "We expect that growth during 2014 will accelerate as the year progresses." It's hard to argue with an endorsement like that.